The present invention relates to motor-vehicle lights of the type comprising:
a hollow body having a front aperture covered by a transparent element and a main reflective structure facing the transparent element, and
a light source located on one side of the hollow body, to which there is associated an auxiliary reflective element, to direct light rays emitted by the source towards the main reflective structure, which is adapted to reflect them towards the transparent element, so as to obtain a light beam having predetermined characteristics coming out from the transparent element.
A motor-vehicle light of the above indicated type is disclosed for example in European Patent Application EP-A-0 886 101. This known light has a number of characteristics aiming to the object of obtaining a minimum bulk of the light in a direction orthogonal to the transparent element, while ensuring that a light beam having the required characteristics is obtained at the output, even in case the light is positioned at an area of the vehicle which is not ideal for obtaining a good rear illumination, such as at a side edge of the rear portion of the motor-vehicle.
The present invention starts from the above mentioned known light and has as its main object that of improving this light in order to obtain new and unique aesthetical effects, both in the condition of light turned off and in the condition of light turned on, which can be exploited to confer unique aesthetical features to the motor-vehicle.
In order to achieve this object, the invention provides a light having the features indicated at the beginning and further characterized in that:
the transparent element has at least a substantial part thereof with no optical elements, so that said main reflective structure is visible from the outside,
said main reflective structure has a shell-like configuration, with a plurality of optically active surface sectors alternated to connecting walls which are substantially radial relative to the source and therefore appear as non-illuminated areas to the viewer, thus ensuring an optical effect characterized by illuminated sectors alternated to non-illuminated sectors,
the above mentioned optically active surface sectors are geometrically generated by translation or rotation from a family of respective generating curves each having undulations with a pitch substantially lower than the pitch of the distribution of the optically active surface sectors.
In the light according to the invention, similarly to the light disclosed in EP-A-0 886 101, the light source with the auxiliary reflective element associated thereto are partially or totally hidden from view. However, in the case of the present invention, the transparent element of the light, at least for a substantially portion thereof, has no optical elements (prisms or lenses) so that the surface of the main reflective structure is visible from the outside. This constitutes an important difference of the light according to the invention with respect to the lights according to the conventional art, in which the transparent element is shaped with prisms or lenses in order to confer predetermined characteristics to the light beam reflected towards the transparent element.
Naturally, since the light according to the invention has no optical elements on the transparent element which are able to confer the required characteristics to the light beam, this function must be obtained by different means. Just to this end, the above mentioned undulations are provided in the curves generating the optically active surfaces sectors. Due to this features, the main reflective structure reflects a light beam which already has the required vergence characteristics towards the transparent element.
In the preferred embodiment, each optically active surface sector is geometrically generated by linear translation of a conic curve (i.e a curve corresponding to the intersection between a plane and a conical surface) having a focus located in proximity of the light source. The above mentioned conic curve may be for example a parabola. In a variant each optical active surface sector is geometrically generated by rotation of a conic curve having a focus located in proximity of the light source.
Preferably, each generating curve is oriented so as to give rise to an optically active surface sector which reflects the rays in the desired direction. In this manner, the various portions of the main reflective structure can reflect the beam according to different angular ranges, so as to obtain a light beam having the required characteristics coming out of the light, notwithstanding the transparent element has no optical elements.
In a further embodiment, each optically active surface sector is geometrically generated by translating or rotating the respective generating curve according to an undulated path. In this case, the main reflective structure thus has both the undulations deriving from the undulated profile of the generating curve, and the undulations, substantially orthogonal to the former, deriving from the undulated path generating the surface.
A further feature of the preferred embodiment of the invention lies in that said auxiliary reflective element is in form of a semi-ellipsoid having the light source in proximity of the focus which is closer to the apex of the semi-ellipsoid. In this case, if the curves generating the optically active surface sectors are parabolas, each generating parabola has the focus located between the two foci of the auxiliary reflective element.
Alternatively, the auxiliary reflective element may have a shape chosen among the paraboloid shape, the cylindrical shape generated by translation of an ellipse, or a complex shape including geometrically different portions.
A further possible feature of the invention lies in that the transparent element, although having a substantial portion with no optical element, anyway has a further minor portion shaped with lenses or prisms. For example, this portion may be a peripheral portion of the light.
A further feature of the preferred embodiment of the invention lies in that it comprises a coloured filter located between the source and auxiliary reflective element unit and the main reflective structure. This coloured filter may also have prisms or a matrix of micro-lenses or Fresnel lenses.
Finally, according to a further preferred feature of the invention, the light source is a conventional lamp having one or more filaments, of a type known per se, the filaments being adapted to be used selectively to obtain different functions by the same light. For instance, the same light can be used as tail light or stop light.